Lifepo4 short????

[cainplant]

I've been using my 15 kilowatt system for about half a year now and I was getting sick of it not being balanced because I'm off grid and I didn't really have a means to balance it. So I just spent 3 days balancing my batteries with a generator and when I put them back together I messed up bad..... I prematurely put the main positive wire on while I was still tightening all of the nuts to the batteries. My ratchet has electrical tape up to the top but it's bare at the top and also at the socket. Well I went to Tighten one of the nuts near the main positive and I accidentally touched it while I was tightening and it blew up (in a sense). There was a bright red glow and about 20 huge sparks burst out of where I was working. Thankfully no fire started.

I thought I just screwed up my entire system. There was a large gash on the steel socket and the BMS lead had melted completely off the wire. Luckily when I took a closer inspection, I realized that I was screwing down a positive terminal at the time of explosion and so it shouldn't have destroyed everything, but it did cause damage to the wires and socket. So I'm really confused why that happened because the voltages shouldn't have been much different at all. Can Someone please explain to me what happened here? Could I have possibly caused damage that I'm not able to see?

Thankfully I learned a lot from this experience and I think it might be important to include that the breaker attached from the main positive to the rest of the system was switched off. After putting everything back together it works fine.

 

[upnorthandpersonal]

I realized that I was screwing down a positive terminal at the time of explosion and so it shouldn't have destroy everything, but it did cause damage to the wires and socket. So I'm really confused why that happened because the voltages shouldn't have been much different at all.

Same reason why a mere 12V car battery can do this:

The amount of current you can send though a short with the capacity these batteries hold is huge. It's the same principle as a welder: the ability to deliver huge amounts of currents though a very low resistance at low overall voltage. Even if you short just one cell (with its very low internal resistance), the resistance is so low in a short you can get thousands of amps as a result...

 

[BentleyJ]

The cells are connected in series, every positive cell termianal (except the main + & -) has a connection to the adjacent negative polarity terminal which = Dead Short.

 

[cainplant]

Same reason why a mere 12V car battery can do this:

The amount of current you can send though a short with the capacity these batteries hold is huge. It's the same principle as a welder: the ability to deliver huge amounts of currents though a very low resistance at low overall voltage. Even if you short just one cell (with its very low internal resistance), the resistance is so low in a short you can get thousands of amps as a result...

But that was an actual short from negative to positive,what I did Was main positive to positive.

 

[cainplant]

The cells are connected in series, every positive cell termianal (except the main + & -) has a connection to the adjacent negative polarity terminal which = Dead Short.

Oh yes, I was not thinking about that, that makes sense

 

[cainplant]

The cells are connected in series, every positive cell termianal (except the main + & -) has a connection to the adjacent negative polarity terminal which = Dead Short.

Why did it not destroy the batteries then?

 

[houseofancients]

I've been using my 15 kilowatt system for about half a year now and I was getting sick of it not being balanced because I'm off grid and I didn't really have a means to balance it. So I just spent 3 days balancing my batteries with a generator and when I put them back together I messed up bad..... I prematurely put the main positive wire on while I was still tightening all of the nuts to the batteries. My ratchet has electrical tape up to the top but it's bare at the top and also at the socket. Well I went to Tighten one of the nuts near the main positive and I accidentally touched it while I was tightening and it blew up (in a sense). There was a bright red glow and about 20 huge sparks burst out of where I was working. Thankfully no fire started.

I thought I just screwed up my entire system. There was a large gash on the steel socket and the BMS lead had melted completely off the wire. Luckily when I took a closer inspection, I realized that I was screwing down a positive terminal at the time of explosion and so it shouldn't have destroyed everything, but it did cause damage to the wires and socket. So I'm really confused why that happened because the voltages shouldn't have been much different at all. Can Someone please explain to me what happened here? Could I have possibly caused damage that I'm not able to see?

Thankfully I learned a lot from this experience and I think it might be important to include that the breaker attached from the main positive to the rest of the system was switched off. After putting everything back together it works fine.

And this is why one uses fuses and breakers

Thank the Lord damage seems minimal

 

[BentleyJ]

Why did it not destroy the batteries then?

because it was such a limited duration.